A magnetic field is used in Magnetic Resonance (MR) Imaging to align the nuclear spins of atoms as part of the procedure for producing images within the body of a patient. This magnetic field is referred to as the B0 field. During an MR scan, Radio Frequency (RF) pulses generated by a transmitter or amplifier and an antenna cause perturbations to the local magnetic field and can be used to manipulate the orientation of the nuclear spins relative to the B0 field. Radio Frequency (RF) signals emitted by the nuclear spins are detected by a receiver coil, and these RF signals are used to construct the MRI images.
In most MR-systems to date a volume coil (e.g. quadrature body coil, QBC) is used to transmit the high power signals for spin excitation. For whole body imaging this is the standard setup for up to 3T. For head imaging volume transmitters are applied at 7T and beyond.
In most such magnetic resonance imaging systems, multichannel receive arrays are employed for improved signal reception and accelerated imaging protocols. This holds true for all anatomies and all field strengths.
A disadvantage of current multichannel systems is that there may be coupling between the antennas or antenna elements for each channel.